The female hormones

At every stage of your life, from birth to death, your hormones play powerful roles. The most notable is that of your sex hormones, which trigger the changes that take place in your body over your lifetime.

Hormones are natural chemicals that trigger activity in different organs throughout your body. The body system responsible for producing your hormones is the endocrine system. This consists of several glands, including the pituitary gland (which, for example, secretes growth hormones), the adrenal glands (you have two, and they control energy levels and the stress response), the thyroid gland (which influences metabolic rate and brain function), the thymus gland (which is essential in your immune response), and, of course, the glands of the reproductive system, most notably the ovaries in women and the testes in men. The pancreas, liver, and kidneys are all hormone-secreting parts of the endocrine system, too. In fact, as far as the human body’s communication systems go, the endocrine system is second only to the nervous system.

Estrogen influences your reproductive system and the physical changes that take place during puberty and menopause. The best way to understand how estrogen and the other hormones affect your body is to take a journey through a woman’s life.


Between birth and puberty, the levels of estrogen in a girl’s body remain quite low – girls have enough to differentiate their characteristic sexual organs but not enough to mature sexually.

At some point between the ages of eight and 11 (although sometimes earlier and sometimes later), a part of the brain called the hypothalamus begins to send signals to the pituitary gland, also in the brain, stimulating it to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These important hormones prompt a girl’s ovaries to begin producing larger amounts of estrogen – and this heralds the start of puberty.


No matter at what age it starts, the process of puberty takes around four years. During this time, the female sex hormones – estrogen and also progesterone – and the male sex hormones (also known as androgens), of which the hormone testosterone is the most well known, influence the development of what doctors call secondary sexual characteristics. Secreted by the ovaries, estrogen triggers the breasts to develop and the vagina to darken in color (to become a duller pink, rather than the bright red of childhood). The vaginal walls begin to thicken and produce white mucus. Estrogen also stimulates the distribution of body fat around the bottom, hips, and thighs – giving you your much-desired womanly, hourglass figure. Androgens, which are secreted by the ovaries and the adrenal glands, stimulate the growth of public and underarm hair, as well as growth in your muscles and bones, making them stronger and longer. And, while all this is going on and the activity of your sex hormones is in overdrive, your monthly periods begin.

Into adulthood

At the end of puberty, your bones mature (become strongest) and you reach your full height. This happens at about age 16 to 17 in girls. Although the sex hormones settle down, estrogen, progesterone, and the androgens, in particular, continue to operate in the body, playing a vital part in regulating your menstrual cycle. Each hormone follows its own timetable, rising and falling at different points in your cycle, but all these sex hormones work together to keep your periods as regular as possible (roughly on a 27- to 33-day cycle, although the length of a regular cycle varies form woman to woman). That’s why if you ever experience irregular periods, you shouldn’t ignore them – they are a sure sign that your sex hormones are not in optimal balance.


The dramatic hormonal changes of puberty pale into insignificance compared with the spectacular ones that occur during pregnancy. Once fertilization takes place, estrogen and progesterone levels remain raised at the end of your menstrual cycle (preventing a period), and the developing placenta produces a new hormone known as human chorionic gonadotrophin (HCG). This hormone stimulates the ovaries to produce even larger amounts of estrogen (to maintain the thickness of the uterus lining) and of progesterone (to prepare the uterus for successful, secure implantation And prevent your body from rejecting the embryo). HCG is the hormone detected by most pregnancy tests.

After three to four months, the well-established placenta takes over from the ovaries as the main producer of estrogen and progesterone. Large amounts of these hormones cause your uterus lining to thicken further and increase the blood supply to your uterus and breasts. They also encourage the muscles of your uterus to relax so it can expand for the growing baby. Eventually, these hormones stimulate contractions in labor and encourage the production of breast milk.

After pregnancy, hormone levels drop sharply. This drop encourages your uterus to shrink back nearly to its original size and your muscles to firm up again. It’s also thought to be the reason why many mothers experience the “baby blues”.


Eventually, when your ovaries run out of eggs, your periods will stop altogether. This is called menopause. Between the age of 35 and 50, a woman enters a phase called the peri-menopausal years, when ovarian production of estrogen and progesterone begins to decline in preparation for menopause. During this time your periods may become irregular, or heavier or lighter than usual. These gradual hormonal changes may also affect other functions or aspects of your body, such as your sleep, memory, and body-fat distribution.


Produced by some plastics and pesticides, xenoestrogens are chemicals similar in structure to estrogen. They can confuse your body, sometimes causing early puberty, and may increase your risk of breast cancer. Reduce your exposure to xenoestrogens by following hormone-balancing diet. Also:

• Reduce your intake of food and drinks that come in plastic containers and avoid heating food in plastic contains (including putting hot or warm drinks in plastic bottles).
• Watch your weight – xenoestrogens are stored in body fat and overweight people tend to have higher concentrations.
• Buy natural household cleaning products
• Use natural, organic toiletries, especially for products that you rub into your skin

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